TOMORROW'S elections throughout much of the United States are the starting guns for next year's congressional and presidential elections. And if precedent holds true, there should be a rising stock market during 1992 - what some market watchers dub an "election-year factor." Currently, there are enough imponderables about the tepid US economy to make some analysts wonder if the past will easily repeat itself."Historically, there's been a significant relationship between a presidential election and the course of the stock market," says Larry Wachtel, an analyst with Prudential Securities Inc. The reason is that "the party in power pulls out all the stops to stimulate the economy," thus seeking to ensure a victory in November. "It is no coincidence" that in almost all recent presidential elections, "the Dow Jones industrial average hit its yearly high just around election time, usually within the last four months of the election" campaign, says James Stack, a market analyst who publishes InvesTech, a newsletter. Mr. Stack has studied the stock market and US economic performance for all presidential election years occurring over the past 100 years. In the past half-century, stock market patterns have been relatively easy to measure, since so much statistical data has become available. Stack concludes that on a historical basis, from the first quarter low for the stock market in an election year - as measured, for example, by the Dow - to the market high recorded sometime during the same year, the market has risen by an average of 21 percent. The Dow, as of now, has been running slightly above 3,000 points. So even if the Dow fell back to 2,900 points sometime in the next few months, if the election-year factor repeated itself, that would mean "an average gain of over 600 points;" such a gain would carry the Dow into the mid-3,000 range next year, Stack says. "There is a tremendous incentive for the White House and the Federal Reserve Board to stretch out this recovery as long as possible, so the economy picks up steam in the second or third quarter of 1992," says Stack. Many economists fret that the recovery is far too slow. But Stack believes that the White House and the Fed would rather see a weak start to the current recovery, rather than a robust recovery in which the Fed would be forced to raise interest rates next year to cool things off. By Congressional design, the Fed is a quasi-independent political body. But the reality is that the Fed is highly political, Stack says, since its governors are appointed by the party in power. Republicans have controlled the Whi te House since 1980. Stack predicts that the stock market will continue to post gains, although he sees a modest correction of about 10 percent or so early in 1992. But then the market will start back up, he says, as the nation steams toward November's presidential election. Stack currently likes secondary stocks rather than the expensive shares of blue-chip companies that dominate the Dow. Mr. Wachtel says the historical pattern about a rising election-year stock market is not necessarily valid this time around. "The White House faces a federal deficit of around $350 billion; anything that Washington does on a fiscal basis [to stimulate the economy] will only expand that deficit." Another factor that could upset the "rising market" thesis for next year is the unusual slowness of national growth. As noted by David Hale, chief economist for Kemper Securities Group Inc., since President Bush took office, "the US economy has expanded by only 0.3 percent at average annual rates." Thus, even if US growth next year chugs along at about 3 percent - the range assumed by the White House - the average annual growth for the US will have been only 1.4 percent under Bush. That's the lowest growth under any president since World War II. But such low growth makes the US vulnerable to a double-dip recession.